The invention relates to a motor drive for camera, and more particularly, to a motor drive which can be mounted and used in a camera of either type including a mechanical shutter release mechanism or electromagnetic shutter release mechanism.
As is well recognized, a shutter release mechanism of a photographic camera can be categorized into a mechanical type and an electromagnetic type. A camera including a mechanical shutter release mechanism has a member connected to the shutter release mechanism and which is engaged by a transmission member of a motor drive of the type which can be mounted in such camera. As a motor of the motor drive rotates, the transmission member is displaced to urge its engaged member for movement, thereby triggering the shutter release mechanism of the camera. On the other hand, a camera including and electromagnetic shutter release mechanism need only be provided with a terminal which receives a shutter release signal from an associated motor drive. A motor drive which is mounted on such camera supplies a shutter release signal which is transmitted through the terminal to trigger the shutter release mechanism.
Thus there have been two kinds of motor drives for use in a camera including a mechanical shutter release mechanism and another camera including an electromagnetic shutter release mechanism. However, it will be appreciated that the provision of separate kinds of motor drive for use with different types of cameras represents an economic disadvantage and a cumbersome operation by a user.
To accommodate for this, a motor drive is contemplated which is designed for use in a camera including a mechanical shutter release mechanism and which is additionally provided with a terminal for transmitting a shutter release signal therethrough so that an electromagnetic shutter release mechanism may also be triggered. However, this involves the following inconvenience:
Specifically, in a camera including a mechanical shutter release mechanism, a motor switch in a motor drive changes from a release side to a winding side in response to a release operation substantially at a coincident timing with the operation of a mirror switch which detects the initiation of a photographing operation within the camera. However, both switches do not always operate concurrently in a camera including an electromagnetic shutter release mechanism, in which a shutter release operation switch of the motor drive, and the camera begins its exposure operation before a release operation within the motor drive is completed. Even though this does not cause a movement of the film due to the provision of a lock mechanism, oscillations produced by the operation of a motor may cause a blurring.
In another camera including an electromagnetic release mechanism in which a control such as a diaphragm control and/or focussing control takes place upon depression of the operating switch before a shutter release operation occurs, an exposure process within a camera may not be initiated when the motor drive has completed its release operation. Since then the motor drive is incapable of determining whether it is before the initiation or after the termination of an exposure process within the camera, a memory storage must be provided in the motor drive for storing the fact that an exposure process has been initiated and terminated. However, this causes another difficulty in a certain motor drive of the type which switches automatically between a release mode and a winding mode by mechanically detecting an increase in the winding torque as an indication of the completion of a film winding operation. In this instance, the mechanical arrangement is such that the termination of exposing the entire film is detected by the failure of a camera to begin a photographing operation in response to a release operation performed under the drive from the motor. Accordingly, if a memory storage is provided in such motor drive, the operating switch must be depressed twice to initiate a film winding operation when the motor drive is mounted in and used for the first time in a camera having an unexposed film, which is inconvenient.